1. Essentials of Human Anatomy & Physiology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slides 7.1 – 7.22 Seventh Edition Elaine N. Marieb Chapter 7 The Nervous System Lecture Slides in PowerPoint by Jerry L. Cook

2. Functions of the Nervous System Slide 7.1a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Sensory input – gathering information  To monitor changes occurring inside and outside the body  Changes = stimuli  Integration  To process and interpret sensory input and decide if action is needed

3. Functions of the Nervous System Slide 7.1b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Motor output  A response to integrated stimuli  The response activates muscles or glands

4. Slide 7.2 Structural Classification of the Nervous System Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Central nervous system (CNS)  Brain  Spinal cord  Peripheral nervous system (PNS)  Nerves outside the brain and spinal cord

5. Functional Classification of the Peripheral Nervous System Slide 7.3a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Sensory (afferent) division  Nerve fibers that carry information to the central nervous system Figure 7.1

6. Functional Classification of the Peripheral Nervous System Slide 7.3b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Motor (efferent) division  Nerve fibers that carry impulses away from the central nervous system Figure 7.1

7. Functional Classification of the Peripheral Nervous System Slide 7.3c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Motor (efferent) division  Two subdivisions  Somatic nervous system = voluntary  Autonomic nervous system = involuntary Figure 7.1

8. Organization of the Nervous System Slide 7.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.2

9. Nervous Tissue: Support Cells (Neuroglia) Slide 7.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Astrocytes  Abundant, star-shaped cells  Brace neurons  Form barrier between capillaries and neurons  Control the chemical environment of the brain Figure 7.3a

10. Nervous Tissue: Support Cells Slide 7.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Microglia  Spider-like phagocytes  Dispose of debris  Ependymal cells  Line cavities of the brain and spinal cord  Circulate cerebrospinal fluid Figure 7.3b, c

11. Nervous Tissue: Support Cells Slide 7.7a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Oligodendrocytes  Produce myelin sheath around nerve fibers in the central nervous system Figure 7.3d

12. Nervous Tissue: Support Cells Slide 7.7b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Satellite cells  Protect neuron cell bodies  Schwann cells  Form myelin sheath in the peripheral nervous system Figure 7.3e

13. Nervous Tissue: Neurons Slide 7.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Neurons = nerve cells  Cells specialized to transmit messages  Major regions of neurons  Cell body – nucleus and metabolic center of the cell  Processes – fibers that extend from the cell body

14. Neuron Anatomy Slide 7.9a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Cell body  Nissl substance – specialized rough endoplasmic reticulum  Neurofibrils – intermediate cytoskeleton that maintains cell shape Figure 7.4a

15. Neuron Anatomy Slide 7.9b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Cell body  Nucleus  Large nucleolus Figure 7.4a

16. Neuron Anatomy Slide 7.10 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Extensions outside the cell body  Dendrites – conduct impulses toward the cell body  Axons – conduct impulses away from the cell body Figure 7.4a

17. Axons and Nerve Impulses Slide 7.11 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Axons end in axonal terminals  Axonal terminals contain vesicles with neurotransmitters  Axonal terminals are separated from the next neuron by a gap  Synaptic cleft – gap between adjacent neurons  Synapse – junction between nerves

18. Nerve Fiber Coverings Slide 7.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Schwann cells – produce myelin sheaths in jelly-roll like fashion  Nodes of Ranvier – gaps in myelin sheath along the axon Figure 7.5

19. Neuron Cell Body Location Slide 7.13 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Most are found in the central nervous system  Gray matter – cell bodies and unmylenated fibers  Nuclei – clusters of cell bodies within the white matter of the central nervous system  Ganglia – collections of cell bodies outside the central nervous system

20. Functional Classification of Neurons Slide 7.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Sensory (afferent) neurons  Carry impulses from the sensory receptors  Cutaneous sense organs  Proprioceptors – detect stretch or tension  Motor (efferent) neurons  Carry impulses from the central nervous system

21. Functional Classification of Neurons Slide 7.14b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Interneurons (association neurons)  Found in neural pathways in the central nervous system  Connect sensory and motor neurons

22. Neuron Classification Slide 7.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.6

23. Structural Classification of Neurons Slide 7.16a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Multipolar neurons – many extensions from the cell body (all interneurons are like this!) Figure 7.8a

24. Structural Classification of Neurons Slide 7.16b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Bipolar neurons – one axon and one dendrite Figure 7.8b

25. Structural Classification of Neurons Slide 7.16c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Unipolar neurons – have a short single process leaving the cell body (common with senses, all sensory) Figure 7.8c

26. Functional Properties of Neurons Slide 7.17  Irritability – ability to respond to stimuli  Conductivity – ability to transmit an impulse  The plasma membrane at rest is polarized  Fewer positive ions are inside the cell than outside the cell=more negative charge inside than out (DNA/protein is negative inside!)

27. Starting a Nerve Impulse Slide 7.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Depolarization – a stimulus depolarizes the neuron’s membrane  A deploarized membrane allows sodium (Na + ) to flow inside the membrane  The exchange of ions initiates an action potential in the neuron Figure 7.9a–c

29. The Action Potential Slide 7.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  If the action potential (nerve impulse) starts, it is propagated over the entire axon (all or none principle)  Potassium ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane  The sodium-potassium pump restores the original configuration  This action requires ATP

32. Nerve Impulse Propagation Slide 7.20 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Impulses travel faster when fibers have a myelin sheath Figure 7.9c–e

33. What is the purpose of the refractory period?

34. Continuation of the Nerve Impulse between Neurons Slide 7.21 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Impulses are able to cross the synapse to another nerve  Neurotransmitter is released from a nerve’s axon terminal  The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter  An action potential is started in the dendrite

35. How Neurons Communicate at Synapses Slide 7.22 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.10

36. Now watch! http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter 14/animation__the_nerve_impulse.htmlhttp://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter 14/animation__the_nerve_impulse.html